It has been stated that “the quest for the elimination of tonsillectomy-associated morbidity has vexed several generations of otolaryngologists” (Colen 2008). Indications for the excision of palatine tonsils (hereinafter referred to as “tonsils”) in pediatric populations are recurrent or chronic tonsillitis, and hypertrophic tonsils with obstructive sleep-disordered breathing (OSDB). Severe OSDB with sleep apnea is associated with serious morbidity, and mild-to-moderate OSDB with significant neurobehavioral morbidity affecting memory, cognition, and school performance (Galland 2006). In recent years, tonsillar hypertrophy has surpassed tonsillitis as the primary indication for tonsillectomy in children. In adults the primary indication is tonsillitis. There are approximately 900,000 tonsillectomies yearly in the United States.
The tonsils are organs of the immune system that are located on the lateral walls of the oropharynx, where in health they may be seen as a pair of roughly ellipsoid structures. The tonsillar capsule, a thin, dense layer of connective tissue covering the lateral surface of the tonsil, is an important anatomical reference point. Immediately under the capsule is a loose connective tissue layer, and under that layer are muscles of the pharynx used in swallowing. These muscles adjacent to the capsule form the tonsillar bed. The capsule does not extend to the exposed medial surfaces of the tonsils, instead, like the rest of the oropharynx, the exposed surface of the tonsil is a mucosal layer consisting of epithelium with an underlying lamina propria. However, the surface of the tonsil is distinguished by many diverticula (“crypts”), which vary in size but which extend in depth to the capsule. The capsule in turn extends into the tonsil parenchyma to form fibrovascular septa that divide the tonsil into multiple lymphatic tissue lobes.
At birth there is only an incipient tonsil, but soon thereafter there is rapid proliferation of lymphoid cells and commensurate expansion of the size of the tonsils. The immune activity of the tonsils is greatest in early childhood. By the second decade of life the lymphoid component of the tonsil begins to involute, and the fibrovascular tissue of the capsule and septa increases in proportion, such that the tonsil atrophies as a person ages, becoming smaller once again but also more fibrotic (Isaacson 2007).
An MRI study (Arens 2002) of children aged 1 to 11 years without tonsil disease showed that the average intertonsillar distance along a line across the airway passing through the center of both tonsils is approximately 7 mm, regardless of age. The combined width of both tonsils along this line increases from about 33 mm to 42 mm, with increasing age in this population. Thus, even with normal growth, the tonsils of young children are very large relative to the airway. Tonsillar hypertrophy involves an abnormal expansion of the lymphoid component of the tonsil such that the airway is compromised. Although adults commonly have tonsils removed as part of a uvulopalatopharyngoplasty (UPPP) procedure for obstructive sleep apnea, tonsillar hypertrophy (with or without adenoidal hypertrophy) as the cause of OSDB is a pediatric condition. The minimum prevalence of childhood obstructive sleep apnea has been estimated as approximately 2 to 3% (Young 2002). In the United States alone, based on most recent census data and considering only the population of 40 million children aged 9 years and younger, this prevalence corresponds to 800,000 to 1,200,000 children with OSDS. The American Academy of Pediatrics has recently recommended screening of all children over one year old for snoring.
Tonsillitis occurs in both adult and pediatric populations when the immune cells of the tonsils are overwhelmed by a pathogen. Antibiotics are frequently ineffective in preventing acute tonsillitis in patients with recurrent tonsillitis. The reason for this lack of efficacy may be the formation of biofilms by bacteria in the tonsillar crypts (Chole 2003). Inflammation leads to fibrosis or scar tissue production in the tonsils of patients with recurrent or chronic tonsillitis.
The pathophysiology of hypertrophic tonsils differs from tonsils with recurrent, chronic tonsillitis. Blood flow to hypertrophic tonsils is significantly greater than blood flow to normal control tonsil, whereas in chronic tonsillitis the blood flow is reduced (Ozdemir 1985). Data from a morphologic study of the oropharynx of children undergoing tonsillectomy indicate that hypertrophic tonsils are less dense than tonsils from tonsillitis patients (Brodsky 1989).
Tonsils in patients with either recurrent, chronic tonsillitis or tonsillar hypertrophy show a wide range in size. Tonsils removed from 31 children treated for OSDB ranged in volume from 5 ml to 18 ml with mean 10.18 ml (Arrarte 2007). This range is similar to the range of tonsil mass (3 to 18.2 g, mean 8.8 g) in 45 children with recurrent tonsillitis (Stearns 1983). In a recent study of patients with tonsillar hypertrophy, or recurrent or chronic tonsillitis, 50 patients aged 2 to 12 years had tonsil weight ranging from 4.0 to 17.6 g (mean 8.7 g), and in 50 patients aged 12 to 47 years, the range was 4.8 to 19.8 g (mean 9.4 g) (Michel 2008).
The tonsillectomy procedure is essentially the same regardless of indication, patient age, or size of tonsils. The tonsils are excised with a surgical plane in the loose connective tissue between the tonsillar capsule and the pharyngeal muscle of the tonsillar bed. In this way, the lymphoid tissue of the tonsil is removed completely, and damage to the muscle in minimized.
A number of different cutting tools can be used to excise the tonsils, for example “cold steel” instruments (knife, scissors, snare, or scalpel), with ligation or electrocautery to control bleeding, or “hot” instruments such as monopolar or bipolar electrocautery, and laser (CO2 or frequency doubled Nd:YAG). Differences between these methods depend on the amount of residual thermal damage produced in the tonsillar bed: cold techniques are associated with little or no residual damage and less postoperative pain, while electrocautery produces more residual damage but also provides the best intraoperative hemostasis. In recent years newer technologies have been developed and used for tonsillectomy; these include ultrasonic dissection (Harmonic Scalpel, Ethicon Endo-Surgery, Cincinnati, Ohio), plasma-assisted radiofrequency ablation (Coblation, ArthroCare Corporation, Sunnyvale, Calif.), argon plasma coagulation (Erbe Elektromedizin GmbH, Tubingen, Germany), and pressure assisted tissue-welding (ENTceps, Starion Instruments Corporation, Sunnyvale, Calif.). Regardless of technology used and the care taken to minimize injury, the end result of excision of the tonsils is an open wound at the tonsillar bed that heals by secondary intention over a period of several days. Pain during healing from tonsillectomy is attributable to nerve irritation, inflammation, and muscle spasm in the pharyngeal wall and is a substantial morbidity that can also lead to decreased oral intake, dehydration, and infection. A recent study in adults has shown a mean duration of significant post-tonsillectomy pain of 11 days, and that pain remained relatively unchanged for the first 5 days after surgery (Salonen 2002). Adults frequently require 2 weeks of recovery after tonsillectomy before returning to work (Magdy 2008). Many adults with chronic or recurrent tonsil disease forgo treatment because of an unwillingness or inability to undergo the prolonged and painful recovery. Children have moderate to severe pain for at least 2 days after tonsillectomy despite pain medication, and typically require several days to resume normal activities. Pain upon swallowing during recovery can lead to dehydration and readmission to hospital. Post-tonsillectomy child-care involves missed work for parents and additional economic costs of treatment. The increased importance of hypertrophic tonsils as an indication for tonsillectomy has led to more very young patients in recent years. The risks of dehydration and bleeding are more serious in small children, and have been an additional motivation for finding a procedure that minimizes postoperative pain and risk of bleeding (Derkay 2006).
In both children and adults, most serious complication of tonsillectomy is bleeding. The incidence of post-operative bleeding is approximately 5%, and is classified as primary when it occurs within 24 hours of surgery and secondary when later. Secondary bleeding is caused when sloughing of the surgical eschar exposes the stumps of tonsillar vessels, and most often occurs between 4 and 7 days after surgery (Windfuhr 2008). Secondary bleeding can be life-threatening and is particularly dangerous because it occurs when the patient is away from immediate medical care. Children are particularly at risk of the consequences of secondary bleeding due to their smaller hemodynamic reserve (Okuyucu 2008). The incidence of secondary post-operative bleeding has remained constant at 1 to 3% regardless of developments in tonsillectomy technique (Colen 2008, Windfuhr 2008). Approximately half of all patients with bleeding return to the operating room (Bhattacharyya 2001).
Adenoidectomy is frequently performed with tonsillectomy in children however adenoidectomy has a low risk of pain and bleeding. Morbidities following tonsillectomy with adenoidectomy are attributable to the tonsillectomy portion of the procedure.
As a consequence of the inherent morbidities of excisional tonsillectomy, there has been recent interest in the alternative of partial tonsillectomy (also known as intracapsular tonsillectomy, or tonsillotomy), in which the surgeon removes a large portion of the tonsils but leaves a barrier of tissue over the capsule. Over the past 15 years various techniques have been used to debulk the tonsils in a partial tonsillectomy, including CO2 laser, Coblation and powered microdebrider (Straightshot, Medtronic Xomed, Jacksonville, Fla.). However, when compared with standard excisional tonsillectomy, partial tonsillectomy has shown a reduction in postoperative pain only after the first two postoperative days (Chang 2008). While partial tonsillectomy preserves tissue that acts as a “biological dressing” and may reduce pharyngeal muscle inflammation and irritation, there is still an open wound at the tonsillar bed that must heal by secondary intention after surgery. Partial tonsillectomy does not eliminate the problem of secondary post-operative bleeding.
The recent tonsillectomy literature states that “despite significant refinements in surgical technique, instrumentation and anesthesia delivery, postoperative complications and relatively slow return to normal diet and activities remain significant challenges for surgeons and patients alike” (Roth 2008). The morbidities and socioeconomic burden of this very common procedure remain significant. The present invention is directed at providing an apparatus and method for treatment of tonsillar disease that has the following benefits: no postoperative bleeding, greatly reduced postoperative pain, minimal or no intraoperative bleeding, more rapid postoperative return to normal activity, ease of use and brief learning curve, shorter procedure time, reduced costs and economic burden, and ability to be performed under local anesthesia in older children and adults.